Whatever they don't want on their platform beyond that is their business. If they don't like videos of baby sea lions, well, I'd have to find my baby sea lion videos elsewhere.
Who defines the terms "Nazis" and "terrorists"
These terms are whatever the moderator says they are. If their definition does not match up with mine, I complain. If it does match, I don't.
Child porn is illegal and has a clear legal definition. We don’t argue as a society over what is or isn’t child pornography. We don’t look at puppy videos and complain to others that it’s child pornography.
We do have people simply express discomfort with how our government behaves, legitimate concerns with immigration, civil rights, or other aspects of society, blanket labeled as nazi’s or extremists and banned from online forums.
It’s dangerous, and it’s being used as an excuse to shutdown speech and information now, specifically more and more to one side of the debate.
So he asked a legitimate question.
Define nazi, because much like labeling people as communists simply because they want better access to healthcare, these terms are being used fast and loose these days to describe anyone someone else may politically disagree with, even when it bears no resemblance to the person being labeled.
I agree with spaginal that child pornography isn't a very grey area. If you're asking people to decide who is and isn't a Nazi, I believe you'll get much more different ideas than if you're asking about child pornography. Is Sam Harris a Nazi? Is Joe Rogan? They were named as far right-adjacent and far right influences in a report - would they be banned from Youtube under your idea?
On their platform, YouTube does.
I apologize if I'm accidentally misunderstanding what your expectations are regarding decisions in society, but if you're asking for society to eliminate judgement calls, this is an incredibly unrealistic ask and you will almost certainly forever be frustrated.
Everyday humans make judgement calls, and they seem to be reasonable far more often than they are unreasonable. If YouTube's userbase feels YouTube has become unreasonable, they move on to another platform. Whether you realize it or not, in a society based on private property, where we allow individuals to have control over things they own, what may seem like arbitrary judgement calls are necessarily made thousands of times per day. Everything from the local bartender who must decide when someone has too much to drink to the person choosing which stocks to buy, to the interviewer deciding who the best candidate is for a job. Judgement calls are constantly made. In a society which worships private property and places an incredibly high value on individual choice, Asking "who decides X, Y, and Z?" will always end with "The person who owns the thing or is placed in the trusted role for that decision." You interact with this trust over and over and over again throughout your day.
Now if you want to question whether or not a society should worship private property to the level with which we do, this is an entirely different question. But in our current iteration, where we trust individuals to make decisions without seeking permission from every member of society, the owners of something or the people they hire decide what is or is not do with their personal assets.
It likely isn't possible to run a society where no one is ever making judgement calls. Again, if I misunderstood the implications of your question, I apologize.
So YouTube actually voluntarily surrendered the right many of you suppose it has in exchange for a privilege — if YouTube removed content that way, it becomes liable for any acts of commercial copyright infringement.
Giving up the power to pick and choose what sort of content would be allowed on their platform seems like something no sane organization would give away. That would be like hackernews signing an agreement where they wouldn't be allowed to moderate, highly unlikely.
I agree that they'd be the ones to make that call on their platform in general, but I don't think they do or even want to. They rely on society to tell them what is and isn't acceptable.
I always have problems when somebody reaches for terms like Nazis and terrorists in an effort to censor/deplatform people, because I feel like it's a trap. On the one hand: who is against literal Nazis? On the other hand: I've been called a Nazi before, and I'm pretty sure I'm not a Nazi, so now I don't know if I'll be included in the proposed banning, or if it's just about literal Nazis. That's why I tend to ask for a definition.
Sure, there's always a grey area between OK and not OK, but I think for things like violence, abuse etc that area is quite small. For things like "Nazi" it is when you're taking it literally, but it's very much not when you're looking at modern circumstances, where some people declare everyone a Nazi that is to the right of them. That might work if they were very far right and saying "there's no acceptable position to my right", but they are usually pretty far left, and I don't agree that there's no position to their right that is acceptable.